The invention concerns the bearings for a gear in a vehicle transmission.
Modern, heavy duty vehicle transmissions predominately exhibit a main transmission gear grouping with a multistage, basic gear train and an integrated, forward placed split group and a subsequent auxiliary drive grouping. These predominately possess, in a transmission housing, a first shaft, termed an input shaft, and a centrally placed second shaft, hereinafter known as a main shaft, as well as one or more counter shafts. The input shaft and the main shaft, in this arrangement, are concentric.
The existing problem solution in accord with the state of the technology, calls for gears being placed in the area between the input shaft of a transmission and the main shaft and radially supported by bearings either on the input shaft or on the main shaft. Contrary to this, in accord with the invention, the proposal is that, in the case of a vehicle transmission having two countershafts placed in its housing for the purpose of load apportionment, wherein one input shaft and one main shaft are arranged coaxially to the input shaft, and with a gear in the zone between the input shaft and the main shaft, the said gear is to be supported axially by a bearing between the input and main shafts and supported radially, by a bearing exclusively between gears of the two counter shafts.
In an advantageous embodiment of the present invention, the bearing system presents exclusively an axial bearing between the input shaft and the main shaft. In a further advantageous embodiment, the axial bearing comprises two axially acting roller bearings which lie on both sides of a projection of the gear. Yet a further advantageous formulation shows the gear as provided for the reception of the axial forces resulting from the toothing of the main shaft and for conducting the axial forces to the input shaft and to the housing.
Because of the invented arrangement, only two bearings are now necessary instead of the previous three axial bearings. In relation to the design of the teeth and the collective load, the demands on the bearings will change and therewith, also their operational life. If the expected wear on the bearings becomes less, then recourse may be made to the designing of smaller sized bearings.
By means of the removal of the radial bearing of the gear on the main shaft, it is no longer necessary to so dimension this so that it extends axially into the zone between the input shaft and the main shaft. By this means, a savings in material in the area of the main shaft can be undertaken.